The present disclosure relates to a complementary metal oxide semiconductor (CMOS) image sensor and a method of manufacturing the same and, more particularly, to a CMOS image sensor in which the doping profile of a floating diffusion region is modified to reduce dark current, and a method of manufacturing the same.
2. Description of the Related Art
There are variety of factors which may degrade the performance of a CMOS image sensor. For example, one such factor is known as dark current. Dark current may exert a significant influence on the imaging functions of a CMOS image sensor, such as for example, on a global shutter principle for simultaneously exposing all pixels. Moreover, a dark current may also cause what is known as a white point, by which a certain pixel appears white due to over-current, thereby degrading the quality of a resultant image.
A dark current may be generated, for example, by current generated in a P/N junction, by electric charges generated in a silicon interface or a surface dangling bond, or by electrons generated due to the state of an STI interface being an isolation layer. Furthermore, as the degree of integration of a CMOS image sensor increases, the dark current generated by shallow trench isolation (STI) interface defects or stress may become a significant difficulty. Also, as the dark current serves as over-current, the reliability of the device may be deteriorated.
Thus, there is a need for an improved CMOS image sensor which decreases dark current and to a method of forming the same.